this.num = 1
const fun = function () {
    const num = 2
    console.log('fun', this.num);
}
const fun2 = function() {
    const num = 3
    console.log('fun2', this.num);
}

const fun3 = function () {
    console.log('fun3', this.num);
}
fun3.num = 6
const obj = {}
obj.num = 5
obj.fun = fun2
const obj2 = new fun3()
fun()
obj.fun()
// obj2()